it's a technology that is of interest to terrorists who want to make their own bombs of any stripe. >> but does it look, when we think about a formal terrorist group, and the sophistication that it would use, does this lend itself to that style of sophistication? i mean, when we talk about pressure cooker bombs, it seems kind of crude. >> yes. so my guess is that this probably is a do-it-yourselfer kind of individual or individuals, perhaps a small group. either one that was inspired by al qaeda or perhaps neonazis or anti-government patriot groups who have been known to act on patriots day. so the date of the attack suggests that we not overlook the possibility that this could be an american anti-government group. although the type of bomb has most recently been attempted by american jihadists, allegedly promoting al qaeda's vision. >> it still leaves a lot of people wondering where the lead is going to come from that's going to start the investigators on the right trail to find whoever did this. our thanks to dr. jessica stern. thanks for being here. i appreciate it. >> thank you. >